Condensation or rising damp? How to tell the difference

Many Doncaster homes, from 1930s semis to ex-council houses and older terraces, get damp patches at some point. Before anyone pays for treatment, it helps to know which kind of damp you are looking at. The two most often confused are condensation and rising damp. This guide is a simple checklist. It is general information, not a diagnosis, and only a survey can confirm the cause.

Signs of condensation

• Black or grey mould in corners, on ceilings, behind wardrobes and around window frames (see black mould removal and causes).
• Streaming windows or damp window sills in the morning.
• Worse in cold weather and in rooms where people cook, shower or dry washing.
• Patches on or near cold external walls, often higher than waist height.
• Walls that feel cold and clammy but are not salt-stained.

Signs of rising damp

• A damp “tide mark” on the wall, typically no higher than about a metre above the floor.
• Crumbling plaster, peeling paint or lifting wallpaper low on the wall.
• White, powdery salt deposits on the surface.
• Rotting skirting boards at the bottom of the wall.
• Present all year round, not only in winter.

True rising damp is less common than people think: GOV.UK guidance says it is usually found in older properties and is often misdiagnosed. Damp low on a wall can also come from a leaking pipe, blocked gutter, high outside ground levels or a bridged damp-proof course, so treatment should only follow a proper look at the cause. Our guide to rising damp and damp proof courses explains what to check.

A simple photo checklist

Photos help whoever looks at the problem, whether that is a landlord, an agent or a surveyor. Take them in daylight, with the date visible on your phone.

1. The whole wall, so the location in the room is clear.
2. A close-up of the worst patch, with a tape measure or ruler next to it for the height above the floor.
3. The window and window sill in that room, first thing in the morning.
4. The outside of the same wall: gutters, downpipes, ground level and any render or pointing.
5. Any extractor fan, with a note of whether it is used.
6. Any mould, and any salt marks or flaking plaster.

Quick questions that point to the cause

• Is it worse in winter or after cooking and showers? That points towards condensation.
• Is it there all year, low down, with salts? That points towards ground moisture.
• Is it on an outside wall below a gutter or window? Look for leaks first.
• Does it follow rain? That suggests penetrating damp rather than condensation.

What you can do first

• Keep rooms ventilated and use extractor fans when cooking and showering.
• Dry washing outside or with a vented dryer where you can.
• Keep furniture slightly away from external walls.
• Wipe condensation from windows and clean mould with a suitable cleaner.
• If you rent, tell your landlord or agent in writing and keep copies. See our guide to damp and mould in rented homes.

When to ask for a damp survey

If the problem keeps coming back, is spreading or you cannot tell what is causing it, ask for a damp survey and a written report before agreeing any work. Our damp survey cost guide explains what a survey should include. If you would like, tell us what you can see using the form on our enquiry page and we will pass your enquiry, with your consent, to a local damp and mould business that covers your area.

Sources and further reading

GOV.UK: understanding and addressing the health risks of damp and mould in the home; Wikipedia: rising damp.

Related guides

• Rising damp and damp proof courses
• Doncaster areas and DN postcodes
• Damp after flooding
• Damp survey cost
• Black mould removal and causes
• Cellar damp and tanking
• Penetrating damp
• Damp and mould in rented homes in Doncaster

Frequently asked questions

How can I tell condensation from rising damp?

Condensation usually shows as mould in corners and on cold walls and is worse in winter, while rising damp shows as a tide mark low on the wall with salts and is present all year. Only a survey can confirm the cause.

Is mould always a sign of rising damp?

No. Mould is far more often linked to condensation from everyday moisture and poor ventilation than to rising damp. GOV.UK guidance notes rising damp is often misdiagnosed.

Can damp low on a wall be something other than rising damp?

Yes. A leaking pipe, a blocked gutter, raised ground outside or a bridged damp proof course can all cause damp low on a wall, so check those before agreeing to treatment.

Should I take photos before reporting damp?

Yes. Dated photos of the wall, the window, the outside of the same wall and any mould help a landlord, agent or surveyor understand the problem.